FIGURE 2.
The effect of drotaverine on neural-mediated inhibitory responses under non-adrenergic non-cholinergic (NANC) conditions and on the degradation of the cAMP in the circular muscle. Representative mechanical recording from the circular muscle showing the relaxation (during the electrical field stimulation) and the off-contraction (rebound after the electrical field stimulation) in control conditions and in the presence of drotaverine 10–6 M (A). Graphs show the effect of drotaverine 10–6 M on electrical field stimulation trains of increasing voltage (5, 6, 7, 8, 10 and 20 V), on the relaxation (left), and the off-contraction (right) (B). Two-way ANOVA (voltage x treatment) was performed without differences with or without drotaverine (treatment p > 0.05). Relaxation was normalized (i.e., 100%) to the basal AUC before electrical field stimulation. Off-contraction was normalized (i.e., 100%) to the maximum amplitude response obtained with a stimulus of 20 V in control conditions. Representative mechanical recording from the circular muscle shows the effect of forskolin (FSK) (left) and the effect of FSK 10–7 M plus drotaverine 10–6, 3 × 10−6, and 10–5 M on the spontaneous phasic contractions (right) (C). Concentration–response curve of FSK (left) and histogram (right) show the effect of drotaverine on the degradation of the cAMP (D). Dunnett’s post hoc test was done after ANOVA to compare the effect of drotaverine with and without FSK, **p < 0.01, ****p < 0.0001. Data were compared with the basal AUC before drug addition. Data were expressed as mean ± SEM.